It is known to provide a crane with a supporting structure, a crane bridge which is movable relative to the supporting structure, and a crane trolley which is movable relative to the crane bridge. Such a crane is used, for example, in a material store in order to transport material between different stations in the material store. Coordinates, for example in the x and y directions, define the precise location of a respective station in a reference system, which has its origin at the supporting structure. The directions x, y are oriented mutually orthogonally. A control device of the crane drives the crane bridge and the crane trolley, in particular by electric motors thereof, such that the crane trolley moves to a respective station. In this case, the control device receives data from a distance measuring system which monitors the positions of the crane bridge and the crane trolley.
Before the crane is put into service, the crane bridge and the crane trolley must be calibrated, so that the actual positions of the crane bridge and of the crane trolley can be calculated directly from the data provided by the distance measuring system.